freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-an.../basic-javascript/manipulate-arrays-with-unsh...

76 lines
1.7 KiB
Markdown
Raw Normal View History

---
id: 56bbb991ad1ed5201cd392ce
title: Manipulate Arrays With unshift()
challengeType: 1
---
## Description
<section id='description'>
Not only can you <code>shift</code> elements off of the beginning of an array, you can also <code>unshift</code> elements to the beginning of an array i.e. add elements in front of the array.
<code>.unshift()</code> works exactly like <code>.push()</code>, but instead of adding the element at the end of the array, <code>unshift()</code> adds the element at the beginning of the array.
</section>
## Instructions
<section id='instructions'>
Add <code>["Paul",35]</code> to the beginning of the <code>myArray</code> variable using <code>unshift()</code>.
</section>
## Tests
<section id='tests'>
```yml
tests:
- text: '<code>myArray</code> should now have [["Paul", 35], ["dog", 3]].'
testString: 'assert((function(d){if(typeof d[0] === "object" && d[0][0] == ''Paul'' && d[0][1] === 35 && d[1][0] != undefined && d[1][0] == ''dog'' && d[1][1] != undefined && d[1][1] == 3){return true;}else{return false;}})(myArray), ''<code>myArray</code> should now have [["Paul", 35], ["dog", 3]].'');'
```
</section>
## Challenge Seed
<section id='challengeSeed'>
<div id='js-seed'>
```js
// Example
var ourArray = ["Stimpson", "J", "cat"];
ourArray.shift(); // ourArray now equals ["J", "cat"]
ourArray.unshift("Happy");
// ourArray now equals ["Happy", "J", "cat"]
// Setup
var myArray = [["John", 23], ["dog", 3]];
myArray.shift();
// Only change code below this line.
```
</div>
### After Test
<div id='js-teardown'>
```js
console.info('after the test');
```
</div>
</section>
## Solution
<section id='solution'>
```js
var myArray = [["John", 23], ["dog", 3]];
myArray.shift();
myArray.unshift(["Paul", 35]);
```
</section>